Monday, 4 March 2013

Early experiences with the new prop

I've got about ten hours of flying in the log with the new propeller and everything seems to be just fine.

It actually makes the Sportcruiser a quite different aircraft in many respects, not just because it is faster. All aspects of the flight envelope are improved, from take-off run to climb rate and cruise speed, to fuel economy.

The aircraft feels different too. The constant speed of the propeller means that the old tell-tale sounds are now largely absent. Where I would notice a small change in engine pitch and start looking for the cause (perhaps an inadvertent nose up or down) now the engine note is constant and after a while it almost fades into the background.

I find that I tend to cruise at around 100 to 105 knots now, where 85 knots was about the going rate with the old propeller. 15-20 knots may not sound like a lot but it is at least 18% faster and that makes for significantly reduced flight times. The speed doesn't fluctuate as much as it used to either.

The sweet spot seems to be at about 18 litres per hour and 100 to 105 knots. This compares with 16 litres per hour and a cruise speed of 85 knots. So I've increased my cruise speed by around 20% for an increase in fuel consumption of 12%. Not a bad result!

On Saturday I flew up to Fife and back along the east coast, past St Abbs to Boulmer and then along the northern edge of Newcastle's zone before heading back to Carlisle. A total distance of 211nm with a flight time of 2h 15m, giving an average speed of 93.8 knots. Given that there was almost 7000ft of climb over the two legs, that ain't at all bad!

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